In situ foam generation within a turbine engine

ABSTRACT

A turbine system includes a foam generating assembly having an in situ foam generating device at least partially positioned within the fluid passageway of the turbine engine, such that the in situ foam generating device is configured to generate foam within the fluid passageway of the turbine engine.

CROSS-REFERENCED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.15/860,347, entitled “IN SITU FOAM GENERATION WITHIN A TURBINE ENGINE,”filed Jan. 2, 2018, which is hereby incorporated by reference in itsentirety for all purposes.

BACKGROUND

The subject matter disclosed herein relates to cleaning of turbineengines. More specifically, the present disclosure relates to generationof cleaning foam.

Turbine engines (e.g., gas turbine engines, such as aircraft engines)typically combust a mixture of carbonaceous fuel and compressed oxidantto generate high temperature, high pressure combustion gases. Thecombustion gases drive a turbine, which may be coupled via a shaft to acompressor. In some embodiments, the shaft may also be coupled to anelectrical generator. In such embodiments, as the combustion gases drivethe turbine and corresponding shaft into rotation, the shaft outputspower to the electrical generator. In aircraft engines, the combustiongases may pass through the turbine and through a nozzle, causing theexhaust gas exiting the nozzle to produce thrust.

Unfortunately, turbine engines are generally susceptible to deposits orcontaminants, such as dust in particular, which may reduce efficiencyand/or effectiveness of the turbine engine. Generally, the deposits andcontaminants may be formed or may gather in any component of the turbineengine, including but not limited to the compressor, the combustor orcombustion chamber, and the turbine. Unfortunately, traditional cleaningsystems and methods utilizing cleaning foam may be imprecise andinefficient. Accordingly, improved cleaning systems and methods areneeded for gas turbine engines.

BRIEF DESCRIPTION

In one embodiment, a turbine system includes a foam generating assemblyhaving an in situ foam generating device at least partially positionedwithin the fluid passageway of the turbine engine, such that the in situfoam generating device is configured to generate foam within the fluidpassageway of the turbine engine.

In another embodiment, an in situ foam generating device of a cleaningsystem for a turbine engine includes an inner fluid path and an outerfluid path concentric with the inner fluid path, wherein the inner fluidpath is configured to receive one of a foaming liquid or an aeratinggas, and wherein the outer fluid path is configured to receive the otherof the foaming liquid or the aerating gas. The in situ foam generatingdevice also includes an interface between the inner fluid path and theouter fluid path, where the interface enables mixing of the aerating gaswith the foaming liquid to generate foam.

In another embodiment, a method of cleaning a turbine engine includesgenerating foam, via an in situ foam generating device, from a foamingliquid and an aerating gas in an area internal to the turbine engine.The method also includes soaking a fluid passageway of the turbineengine with the foam.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a cross-sectional schematic view of an embodiment of a turbinesystem having a turbine engine, a foam generating assembly, and an insitu foam generating device of the foam generating assembly, inaccordance with an aspect of the present disclosure;

FIG. 2 is a cross-sectional schematic view of an embodiment of anaircraft turbine engine having a foam generating assembly with an insitu foam generating device for cleaning the aircraft turbine engine, inaccordance with an aspect of the present disclosure;

FIG. 3 is a cross-sectional schematic view of an embodiment of acleaning volume or fluid passageway of the aircraft turbine engine ofFIG. 2 , in accordance with an aspect of the present disclosure;

FIG. 4 is a plot illustrating certain technical effects associated withthe in situ foam generating device of FIGS. 1 and 2 , in accordance withan aspect of the present disclosure;

FIG. 5 is another plot illustrating certain technical effects associatedwith the in situ foam generating device of FIGS. 1 and 2 , in accordancewith an aspect of the present disclosure;

FIG. 6 is another plot illustrating certain technical effects associatedwith the in situ foam generating device of FIGS. 1 and 2 , in accordancewith an aspect of the present disclosure;

FIG. 7 is a schematic illustration of a portion of the turbine system ofFIG. 1 prior to insertion of the in situ foam generating device into theturbine engine, in accordance with an aspect of the present disclosure;

FIG. 8 is a schematic illustration of a portion of the turbine system ofFIG. 1 after insertion of the in situ foam generating device within theturbine engine, in accordance with an aspect of the present disclosure;

FIG. 9 is a cross-sectional view of an embodiment of an in situ foamgenerating device for use in a foam generating assembly of a turbineengine cleaning system, in accordance with an aspect of the presentdisclosure;

FIG. 10 is a cross-sectional view of another embodiment of an in situfoam generating device for use in a foam generating assembly of aturbine engine cleaning system, in accordance with an aspect of thepresent disclosure;

FIG. 11 is a cross-sectional view of another embodiment of an in situfoam generating device for use in a foam generating assembly of aturbine engine cleaning system, in accordance with an aspect of thepresent disclosure;

FIG. 12 is a cross-sectional view of another embodiment of an in situfoam generating device for use in a foam generating assembly of aturbine engine cleaning system, in accordance with an aspect of thepresent disclosure;

FIG. 13 is a cross-sectional view of another embodiment of an in situfoam generating device for use in a foam generating assembly of aturbine engine cleaning system, in accordance with an aspect of thepresent disclosure;

FIG. 14 is a cross-sectional view of another embodiment of an in situfoam generating device for use in a foam generating assembly of aturbine engine cleaning system, in accordance with an aspect of thepresent disclosure;

FIG. 15 is a cross-sectional view of another embodiment of an in situfoam generating device for use in a foam generating assembly of aturbine engine cleaning system, in accordance with an aspect of thepresent disclosure;

FIG. 16 is a cross-sectional view of another embodiment of an in situfoam generating device for use in a foam generating assembly of aturbine engine cleaning system, in accordance with an aspect of thepresent disclosure; and

FIG. 17 is an embodiment of a method of cleaning a turbine engine with acleaning system having a foam generating assembly that includes an insitu foam generating device, in accordance with an aspect of the presentdisclosure.

DETAILED DESCRIPTION

Turbine engines (e.g., gas turbine engines, such as certain aircraftengines) typically combust a mixture of carbonaceous fuel and compressedoxidant to generate high temperature, high pressure combustion gases,which are utilized in a number of ways depending on the type of turbineengine. For example, the combustion products may cause components of theturbine engine to output power to an electrical generator. Additionallyor alternatively, the combustion products may pass through a nozzle(e.g., in an aero-derivative turbine engine) to produce thrust.

Unfortunately, gas turbine engines are generally susceptible to depositsor contaminants, such as dust in particular, which may reduce efficiencyand/or effectiveness of the turbine engine. Generally, the deposits andcontaminants may be formed or may gather in any component of the turbineengine, including but not limited to the compressor, the combustor orcombustion chamber, and the turbine.

In accordance with present embodiments, a cleaning system for cleaningthe turbine engines such as those described above includes a foamgenerating assembly at least partially positioned internal to theturbine engine. For example, the foam generating assembly includes an insitu foam generating device having a foam outlet that, when the in situfoam generating device is installed during a cleaning procedure, opensinto a fluid passage of the turbine engine. “In situ foam generatingdevice” used in this present specification is intended to mean that thefoam generating device and the target cleaning area are both disposedinternal to the turbine engine, such that the foam is generated withinthe turbine engine and delivered to the target within the turbineengine. In other words, materials to generate the foam are conveyed(e.g., via hoses) into the foam generating device positioned within theturbine engine, which receives the materials and generates the foaminside the turbine engine. In particular, the in situ foam generatingdevice may be positioned within a fluid passageway (e.g., a hot gaspath, a cooling circuit, or both) of the turbine engine, such that thefoam is generated within the fluid passageway and delivered through thefluid passageways to one or more cleaning targets.

As noted above, materials for generating the foam may be individuallyconveyed to the in situ foam generating device. For example, the in situfoam generating device may receive a detergent (e.g., a liquiddetergent, such as a water-based detergent containing citric acid) orother foaming liquid and an aerating gas (e.g., air, nitrogen), and maymix the detergent and the aerating gas to generate bubbles. The bubblesmay be directed from an outlet of the foam generating device towardgeneral and/or targeted areas of the turbine engine for cleaning theturbine engine. The in situ foam generating device may be coupled with adetergent storage source or tank (e.g., via a detergent hose), and anintervening flow biasing device (e.g., a pump) may be controlled tosupply the detergent from the detergent storage tank, through the hose,and to the in situ foam generating device. Likewise, the in situ foamgenerating device may be coupled to an aerating gas source or tank(e.g., via an aerating gas hose), and an intervening flow biasing device(e.g., a fan or blower) may be controlled to supply the aerating gasfrom the detergent storage tank, through the hose, and to the in situfoam generating device. In some embodiments, the detergent hose and theaerating gas hose may be concentric with each other proximate the insitu foam generating device. In other words, in some embodiments, theaerating gas hose may be encapsulated by the detergent hose, or viceversa, adjacent the in situ foam generating device.

As described above, the in situ foam generating device may generate foamin an area internal to the turbine engine (e.g., within a fluidpassageway of the turbine engine). In doing so, foam quality may beimproved compared to embodiments in which foam is generated external tothe turbine engine and subsequently routed to the turbine engine. Forexample, bubbles generated via traditional external generators must berouted into the turbine engine, which may cause undesired expansion ofthe foam bubbles. The undesired expansion of the foam bubbles may causeat least certain of the bubbles to be too large to pass through certainopenings, orifices, or regions of the fluid passageway of the turbineengine. Additionally, as the foam bubbles are routed between thetraditional external foam generator and the turbine engine and grow insize, a large percentage of the foam bubbles may collapse prior tocontacting, soaking, or otherwise adequately cleaning the inside of theturbine engine, thereby reducing an efficiency of the cleaningprocedure. The in situ foam generating device of the present disclosurefacilitates improved bubble diameter and improved bubble collapsepercentages, thereby improving a cleaning precision and efficiency ofthe cleaning system. In other words, since the in situ foam generatingdevice facilitates more precise bubble qualities and does not require alarge traversal distance to the turbine engine, the bubbles are moreeffective and require less resources (e.g., detergent, water, andaerating gas) than traditional embodiments.

Further to the points above, the in situ foam generating device may beconfigured (e.g., sized) such that it is capable of being positionedthrough various ports of the turbine engine (e.g., borescope inspectionports, igniter ports, fuel nozzle orifices), a throat area of theturbine engine (e.g., if properly sized), and/or between rotor bladesand a stator of the turbine engine. Accordingly, the in situ foamgenerating device supplies improved bubbles closer to targeted areasthat would otherwise be difficult to clean in traditional embodiments.In other words, the in situ foam generating device facilitates improvedbubble quality for general cleaning, in addition to improved access totargeted areas of the turbine engine that are traditionally difficult toreach.

Further still, in part because of the advantages described above, morecost effective materials having lower foam stability may be used togenerate the foam in disclosed internal foam generation embodiments. Forexample, since the bubbles in the disclosed internal foam generationembodiments are closer to the areas of the turbine engine requiringcleaning, the bubbles may not need to maintain bubble integrity for aslong as a volume of bubbles that requires passage to the turbine enginefrom an external foam generator. In other words, because the foambubbles in disclosed embodiments are closer to the turbine cleaningareas than those in externally generated embodiments, a higher collapserate may be desired as a means to reduce material cost and reduce acleaning time period. Indeed, using materials with lower foam stabilitymay enable the improved material cost and may enable the shortercleaning time. These and other features will be described in detailbelow with reference to the drawings.

Turning now to the drawings, FIG. 1 is a block diagram of a turbinesystem 10 and a cleaning system 11 configured to clean the turbinesystem 10. The turbine system 10 includes a fuel injector 12, a fuelsupply 14, a combustor 16, and a turbine 18. As illustrated, the fuelsupply 14 routes a liquid fuel and/or gas fuel, such as natural gas, tothe gas turbine system 10 through the fuel injector 12 and into thecombustor 16. As discussed below, the fuel injector 12 is configured toinject and mix the fuel with compressed air. The combustor 16 ignitesand combusts the fuel-air mixture, and then passes hot pressurizedexhaust gas into the turbine 18. As will be appreciated, the turbine 18includes one or more stators having fixed vanes or blades, and one ormore rotors having blades which rotate relative to the stators. Theexhaust gas passes through the turbine rotor blades, thereby driving theturbine rotor to rotate. Coupling between the turbine rotor and a shaft19 will cause the rotation of the shaft 19, which is also coupled toseveral components throughout the gas turbine system 10, as illustrated.Eventually, the exhaust of the combustion process may exit the gasturbine system 10 via an exhaust outlet 20. In some embodiments, the gasturbine system 10 may be a gas turbine system of an aircraft, in whichthe exhaust outlet 20 may be a nozzle through which the exhaust gasesare accelerated. Acceleration of the exhaust gases through the exhaustoutlet 20 (e.g., the nozzle) may provide thrust to the aircraft. Asdescribed below, the shaft 19 (e.g., in an aircraft gas turbine system10) may be coupled to a propeller, which may provide thrust to theaircraft in addition to, or in place of, the exhaust gases acceleratedthrough the exhaust outlet 20 (e.g., the nozzle).

A compressor 22 includes blades rigidly mounted to a rotor which isdriven to rotate by the shaft 19. As air passes through the rotatingblades, air pressure increases, thereby providing the combustor 16 withsufficient air for proper combustion. The compressor 22 may intake airto the gas turbine system 10 via an air intake 24. Further, the shaft 19may be coupled to a load 26, which may be powered via rotation of theshaft 19. As will be appreciated, the load 26 may be any suitable devicethat may use the power of the rotational output of the gas turbinesystem 10, such as a power generation plant or an external mechanicalload. For example, the load 26 may include an electrical generator, apropeller of an airplane as previously described, and so forth. The airintake 24 draws air 30 into the gas turbine system 10 via a suitablemechanism, such as a cold air intake. The air 30 then flows throughblades of the compressor 22, which provides compressed air 32 to thecombustor 16. In particular, the fuel injector 12 may inject thecompressed air 32 and fuel 14, as a fuel-air mixture 34, into thecombustor 16. Alternatively, the compressed air 32 and fuel 14 may beinjected directly into the combustor for mixing and combustion.

The turbine system 10 may be susceptible to gathering of deposits orcontaminants, namely dust, within components of the turbine system 10.Accordingly, as illustrated, the turbine system 10 includes the cleaningsystem 11 fluidly coupled to at least one component of the turbinesystem 10. For example, the illustrated cleaning system 11 includes afoam generating assembly 13 having an in situ foam generating device 15.The in situ foam generating device 15 is illustrated as positionedwithin the turbine 18, although the in situ foam generating device 15may be positioned internal to a different component of the turbinesystem 10, such as the air intake(s) 24, the compressor 22, the fuelinjector(s) 12, the combustor(s) 16, the turbine 18, and/or the exhaustoutlet 20. The in situ foam generating device 15 is configured toreceive a foaming liquid or, more specifically, a detergent (e.g.,liquid citric acid based detergent) from a detergent source or storagetank 17, and aerating gas (e.g., air, nitrogen) from an aerating gassource or storage tank 21. In some embodiments, a surfactant may bemixed with the detergent at the detergent storage tank 17, or at anylocation downstream of the detergent storage tank 17. The in situ foamgenerating device 15 may mix the detergent and the aerating gas to formbubbles inside a fluid passageway 35 of the turbine 18 (and/or othercomponents of the turbine system 10). The fluid passageway 35 mayinclude a hot gas path of the turbine system 10, a cooling circuit ofthe turbine system 10, or both. In general, the in situ foam generatingdevice 15 may be configured (e.g., sized, shaped) to be disposedinternal to the turbine 18 (and/or other components of the turbinesystem 10) by passing the in situ foam generating device 15 through aport of the turbine system 10. As described above and in detail belowwith reference to the drawings, the in situ foam generating device 15enables an improved foam quality compared to traditional embodiments,enhancing an efficiency of the cleaning procedure in terms of both costand time. Although the components of the turbine system 10 in FIG. 1 areillustrated as separate blocks, the components (or certain components)may connected such that the fluid passageway 35 extends continuouslythrough multiple ones of the components of the turbine system 10 (e.g.,the turbine 18, the combustor 16, the fuel injectors 12, the compressor22, the air intake 24, or a combination thereof).

The cleaning system 11 in FIG. 1 is configured to generate, and provideto the component(s) of the gas turbine system 10, a foam output from thein situ foam generating device 15 into the fluid passageway 35 of theturbine system 10. The foam loosens, soaks, absorbs, and/or cleans thedeposits or contaminants, namely dust, within the components of theturbine system 10. The cleaning system 11 may also include componentsconfigured to rinse the gas turbine system 10 after the detergent basedfoam soaks the insides of the components of the gas turbine system 10for a defined period of time. For example, a flushing assembly 23 mayrinse or flush the effluent (e.g., collapsed foam and contaminants) fromthe turbine system 10 (e.g., with jets of water). Although the flushingassembly 23 is illustrated as interfacing with the turbine system 10 ata similar location as the in situ foam generating device 15 of the foamgenerating assembly 13, the flushing assembly 23 may access the turbinesystem 10 at a different location.

FIG. 2 illustrates a cross-sectional schematic view of an embodiment ofthe cleaning system 11 and an aircraft gas turbine engine 40 (e.g.,aero-derivative gas turbine engine) that includes a fan assembly 41 anda core engine 42 including a high pressure compressor 43, a combustor44, a high-pressure turbine (HPT) 45, and a low-pressure turbine (LPT)46. In general, the cleaning system 11 may be equipped with the in situfoam generating device 15 positioned within the fluid passageway 35 ofthe aircraft gas turbine engine 40, as previously described. Theillustrated aircraft gas turbine engine 40 may be an example of the gasturbine system 10 illustrated in FIG. 1 . In the illustrated embodiment,the fan assembly 41 of the gas turbine engine 40 (e.g., aircraft gasturbine engine) includes an array of fan blades 47 that extend radiallyoutward from a rotor disk 48. The gas turbine engine 40 has an intakeside (e.g., proximate the fan assembly 41) and an exhaust side (e.g.,proximate the LPT 46). The fan assembly 41 and the LPT 46 are coupled bya low-speed rotor shaft 49, and the high pressure compressor 43 and theHPT 45 are coupled by a high-speed rotor shaft 51. The gas turbineengine 40 may be any type of gas or combustion turbine aircraft engineincluding, but not limited to, turbofan, turbojet, turboprop, turboshaftengines as well as geared turbine engines such as geared turbofans,un-ducted fans and open rotor configurations. Alternatively, the gasturbine engine 40 may be any time of gas or combustion turbine engine,including, but not limited to, land-based gas turbine engines in simplycycle, combined cycle, cogeneration, marine and industrial applications.

Generally, in operation, air flows axially through the fan assembly 41,in a direction that is substantially parallel to a centerline 53 thatextends through the gas turbine engine 40, and compressed air issupplied to the high pressure compressor 43. The highly compressed airis delivered to the combustor 44. Combustion gas flow (not shown) fromthe combustor 44 drives the turbines 45 and 46. The HPT 45 drives thecompressor 43 by way of the shaft 51, and the LPT 46 drives the fanassembly 41 by way of the shaft 49. Moreover, in operation, foreignmaterial, such as mineral dust, is ingested by the gas turbine engine 40along with the air, and the foreign material accumulates on surfacestherein.

As shown, the cleaning system 11 includes a foam generating assembly 13having the in situ foam generating device 15, the detergent storage tank17 (or source), the aerating gas storage tank 21 (or source), and a hoseassembly 50 for routing the detergent and the aerating gas from thestorage tanks 17, 21 to the in situ foam generating device 15. The hoseassembly 50 in the illustrated embodiment includes, downstream from ahose juncture 54, a dual-hose portion 55 in which the hose assemblyincludes an inner hose that receives either the aerating gas or thedetergent, and an outer hose encapsulating the inner house andconfigured to receive, between an inner wall of the outer house and anouter wall of the inner hose, the other of the detergent or the aeratinggas. However, other arrangements of the hose assembly 50 are alsopossible and will be described with reference to later figures. The insitu foam generating device 15 is configured to receive the aerating gasand the detergent while the in situ foam generating device 15 ispositioned within the aircraft gas turbine engine 40, generate the foam,and supply the foam to the fluid passageway 35. The flushing assembly 23of the cleaning system 11 may be configured to rinse the effluent fromthe fluid passageway after a soaking period lapses. For clarity, anotherexample of an embodiment of the fluid passageway 35 extendingcontinuously through various components of the gas turbine engine 40 ofFIG. 2 (e.g., through at least the compressor 43, the combustor 44, andthe turbine stages 45, 46) is shown in FIG. 3 . In FIG. 3 , the fluidpassageway 35 may include a hot gas path 37 and a cooling circuit 39,where the hot gas path 37 is depicted schematically in FIG. 3 as acenter of the fluid passageway 35, and the cooling circuit 39 isdepicted schematically in FIG. 3 as surrounding the hot gas path 37(e.g., along an edge of the hot gas path 37). It should be noted thatthe cooling circuit 39 may be substantially fluidly isolated from thehot gas path 37. Further, the disclosed in situ foam generating device15 may access the hot gas path 37 and the cooling circuit 39independently or simultaneously.

While FIGS. 7-16 illustrate various aspects of the foam generatingassembly 13 having the in situ foam generating device 15, FIGS. 4-6 arefirst provided and described to depict certain advantages associatedwith in situ foam generation. For example, FIG. 4 includes a plot 60illustrating bubble diameter 62 as a function of bubble traversaldistance 64. In traditional embodiments, foam is generated external to aturbine engine, routed to the turbine engine, and then routed to aparticular location or target 65 within the turbine engine (e.g., asillustrated by the external foam generation bubble size data 66). Usingin situ foam generation in accordance with the present disclosure, thefoam is generated inside the turbine engine, in some cases immediatelyadjacent the target 65 (e.g., as illustrated by the internal foamgeneration bubble size data 68). During foam traversal, the bubblesforming the foam may expand. Since traditional embodiments require alarger traversal distance than the in situ embodiments described by thepresent disclosure, the bubbles may include larger bubble diameters oncethe bubbles reach the target 65. Bubbles having too large of a diametermay have difficulty passing through smaller areas, openings, orifices,or fluid paths inside the turbine, which may reduce an effectiveness ofthe cleaning procedure. Accordingly, the smaller and more controllablebubble sizes associated with internal foam generation may be desired forimproved efficiency and effectiveness of the cleaning procedure. Ingeneral, bubble diameters between 25 microns and 1 millimeter aredesirable. Further, by utilizing the in situ foam generation, thebubbles may expand in size along the traversal distance between the insitu foam generation device and the target cleaning area by no more than500%. In some embodiments in accordance with the present disclosure, thebubbles may increase in size along the traversal distance no more than400%, no more than 300%, or no more than 200%, depending on a proximityof the generating device and the target cleaning area (i.e., thetraversal distance).

It should be noted that, while not included in the plots 60, 70, and 80illustrated in FIGS. 4-6 , foam temperature is another factor dependenton traversal distance. For example, as the foam travels from thegenerating device toward the target cleaning position or region, atemperature of the foam may decrease as energy is lost. By generatingthe foam internal to the turbine engine, the loss of energy ortemperature may be reduced, thereby reducing or negating cleaning cyclesthat produce foam having insufficient temperature. Since the traversaldistance of internally generated foam is less than that of externallygenerated foam, the temperature of the internally generated foam may bemore controllable and less reliant on features involved during foamtraversal (e.g., ambient temperature, imperfections along the traversaldistance, etc.). Additionally or alternatively, in some embodiments, theinitial starting temperature of the internally generated foam may beless than the initial starting temperature of traditional externallygenerated foam, which may reduce a cleaning cost. In accordance withcertain embodiments, the foam may be generated with an initialtemperature of approximately 85-125 degrees Celsius, and may bedelivered to the target cleaning region at a temperature ofapproximately 70-105 degrees Celsius. In general, the temperature of thefoam in accordance with present embodiments may drop by 20% or lessalong the traversal distance from the in situ foam generating device andthe target cleaning area, region, or point.

It should also be noted that FIG. 4 assumes a comparable initial bubblesize between the externally generated foam and the internally generatedfoam. Although it appears as though the externally generated foam couldbe generated with a smaller initial bubble diameter than that of theinternally generated foam such that the externally and internallygenerated foam embodiments include comparable bubble size at the target65, bubbles having different initial bubble diameters behavedifferently. For example, bubbles having smaller initial diameters maycoarsen at a higher rate (e.g., as an inverse function of the bubblediameter or radius) than those having larger initial diameters, whichmay cause a poor bubble size distribution, may cause expansion and/orcollapsing of the bubbles, and in general may reduce an effectiveness ofthe foam. Further, a minimum bubble diameter for foam generated to cleanturbine engines is approximately 0.10 millimeters or 0.05 millimeters,depending on features such as materials/devices used. In other words,bubble diameter is more controllable (and/or evenly distributed) fordelivery to the target 65 with internal foam generation than withexternal foam generation, even if the bubbles in external foamgeneration include smaller initial diameters.

FIG. 5 includes a plot 70 illustrating bubble collapse percentage 72 asa function of the foam traversal distance 64. Similar to the plot 60illustrating bubble diameter 62 as a function of the foam traversaldistance 64, the plot 70 illustrates advantages of internal foamgeneration compared to external foam generation. For example, as thefoam travels between the foam generating device and the target 65, thebubbles forming the foam may expand until they collapse. Of course,certain bubbles will expand and collapse at different rates; thus, thevolume of foam may include a percentage of collapsed foam that increasesas a function of traversal distance 64. Since embodiments havingexternal foam generation require a greater traversal distance (i.e.,represented by the external foam generation collapse percentage data 76in the illustrated plot 70), a larger percentage of the bubbles formingthe foam collapses by the time the volume of foam reaches the target 65than embodiments having internal foam generation (i.e., represented bythe internal foam generation collapse percentage data 78 in theillustrated plot 70). Reducing a percentage of bubbles that collapsebefore reaching the target 65 may improve effectiveness of the cleaningprocedure.

The plot 70 included in FIG. 5 assumes that the same detergent andaerating gas is used for the external foam generation and the internalfoam generation. The illustrated plot 70 illustrates how, assuming thesame materials, the internal foam generation can enable a reduced amountof collapsed bubbles at the target 65.

Additionally or alternatively, internal foam generation may enable theuse of cheaper, less stable materials to generate the foam. For example,FIG. 6 includes another plot 80 illustrating the bubble collapsepercentage 72 as a function of the foam traversal distance 64. Similarto the plots 60, 70 above, the plot 80 illustrates advantages ofinternal foam generation compared to external foam generation. Forexample, cheaper and less stable materials may be selected for theexternal foam generating embodiments such that a rate of bubble collapseis increased compared to internal foam generating embodiments utilizingmore stable materials. Indeed, while FIGS. 5 and 6 both plot bubblecollapse percentage 72 as a function of traversal distance 64, theinternally generated foam data 79 in FIG. 6 includes a different (i.e.,greater) slope than any of the other foam data 76, 78 in FIGS. 5 and 6 ,since the internally generated foam data 79 in FIG. 6 is indicative of afoam formed by less stable, more cost-effective materials than that ofthe other foam data 76, 78. In other words, FIG. 6 illustrates how thereduced traversal distance 64 associated with in situ foam generation,coupled with the use of less stable materials, may result in theinternally generated bubbles of the internal foam data 79 of FIG. 6having the same collapse percentage 72 at the target 65 as externallygenerated bubbles utilizing more stable materials. In addition tomaterial cost savings, the bubbles associated with the internal bubblegeneration data 79 of FIG. 6 and formed by less stable materials willcollapse faster after reaching the target 65 (e.g., during a soakingperiod), which reduces an amount of time required to clean the turbineengine. By reducing a time required for the cleaning period, a turbineengine maintenance period is reduced. The less stable materials mayinclude a more cost effective detergent, a more cost effective aeratinggas, a more cost effective ratio of detergent to aerating gas, a morecost effective surfactant, or a combination thereof. As suggested in theillustrations, the more cost-effective, less stable materials in theinternally generated foam data 79 of FIG. 6 could not be used with anexternal foam generator, since the collapse percentage would be far toohigh.

FIGS. 7 and 8 are schematic illustrations of the foam generatingassembly 13 having the in situ foam generating device 15 being insertedthrough a port 100 of a component of a turbine engine 101. As previouslydescribed, the port 100 may be an existing port (e.g., a borescopeinspection port, an ignitor port, a fuel nozzle orifice, or some otheropening in the turbine engine 101). The in situ foam generating device15 may be sized to fit through the port 100. For example, as illustratedin FIG. 7 , a maximum diameter or width 104 of the in situ foamingdevice 15 is less than a minimum diameter or width 102 of the port 100.The minimum diameter or width 102 of the port 100 may be one inch(approximately 25 millimeters), one half inch (approximately 13millimeters), or one quarter inch (approximately 6 millimeters),depending on the embodiment and/or port 100. Thus, the maximum diameteror width 104 of the in situ foaming device 15 (or the portion thereofpassing through the port 100) may be less than one inch, one half inch,or one quarter inch. Accordingly, as illustrated in FIG. 8 , the in situfoaming device 15 is capable of passing through the port 100 forpositioning inside the component of the turbine engine 101.

As previously described, a hose arrangement 50 may couple the in situfoaming device 15 with the detergent storage tank 17 (or source) and theaerating gas detergent storage tank 21 (or source). The hose arrangement50 may include two separate, side-by-side hoses as shown, or the hosearrangement 50 may include at least a portion having an outer hoseencapsulating an inner hose, where the outer hose routes one of thedetergent or aerating gas, and the inner hose routes the other of thedetergent or aerating gas (e.g., as illustrated in, and described withrespect to, FIG. 2 ). As will be appreciated in view of later figures,the in situ foaming device 15 may include inner and outer fluid pathsthat couple with the aforementioned inner and outer hoses. However, theside-by-side hose arrangement 50 illustrated in FIGS. 7 and 8 may alsobe capable of interfacing with inner and outer fluid paths of the insitu foaming device 15 (e.g., via a manifold or juncture configurationpositioned at or within the in situ foaming device 15). Other aspects ofthe in situ foaming device 15 will be described in detail below withreference to FIGS. 9-16 .

Since the detergent may be a liquid based citric acid detergent, a flowbiasing device such as a pump 108 may be used to route the detergentfrom the tank 17 to the in situ foam generating device 15. As previouslydescribed, the detergent may also include a surfactant mixed therein(e.g., at the tank 17 or elsewhere). A flow biasing device such as a fan110 or blower may be used to route the aerating gas from the tank 21 tothe in situ foam generating device 15. The foam generating assembly 13(e.g., of the cleaning system) may include the in situ foam generatingdevice 15, the hoses of the hose arrangement 50, the pump 108 and thetank 17, the fan 110 and the tank 21, or a combination thereof.

FIGS. 9-16 illustrate various embodiments of the in situ foam generatingdevice. It should be noted that, while certain of FIGS. 9-16 illustratein situ foam generating devices having axisymmetric and/or cylindricallyarranged flow paths and features, any of the illustrated embodiments mayinclude non-axisymmetric and/or non-cylindrical arrangements. Indeed,the devices may be rectangular, triangular, cylindrical, hexagonal,octagonal, irregular, or otherwise shaped. Further, the features (e.g.,inner and outer fluid paths, or other features) of the device may becentered on a longitudinal axis, or one or more of the features (e.g.,the inner fluid path, the outer fluid path, or both, or other features)may be offset from, or not centered on, the longitudinal axis. Certainof FIGS. 9-16 are illustrated and/or described as axisymmetric and/orcylindrical for purposes of clarity, but any of FIGS. 9-16 may includenon-axisymmetric and/or non-cylindrical arrangements.

For example, FIG. 9 is a cross-sectional view of an embodiment of an insitu foam generating eductor 150. In the illustrated embodiment, theeductor 150 includes an outer fluid path 152 configured to receiveliquid detergent (e.g., citric based detergent), an inner fluid path 154configured to receive aerating gas (e.g., air), and an interface 156between the outer fluid path 152 and the inner fluid path 154. The outerfluid path 152 is disposed between the interface 156 and an outer (e.g.,annular) wall 155 of the eductor 150. The inner fluid path 154 and theouter fluid path 152 are arranged about a longitudinal axis 149 (e.g.,the inner fluid path 154 and the outer fluid path 152 are concentric andcentered on the longitudinal axis 149). The interface 156 in theillustrated embodiment is a wall having openings 158 through which theliquid detergent passes from the outer fluid path 152 to the inner fluidpath 154. In some embodiments, a flow biasing device may cause theliquid to pass through the openings 158. Additionally or alternatively,the structure of the eductor 150 may enable the Venturi principle, wherethe flow of the aerating gas through a throat 157 (e.g., Venturi) of theinner path 154 causes a low pressure area proximate the openings 158 ofthe interface 156 that draws the liquid 152 through the openings 158 ofthe interface 156. In other words, the eductor 150 causes the flow ofthe aerating gas through the throat 157 of the inner path 154 to performthe work of pumping the liquid detergent from the outer path 152 intothe inner path 154. The liquid detergent and the aerating gas may mixwithin (and/or downstream of) the throat 157 to generate foam, and thefoam may be output at an outlet 153 of the eductor 150. An island 159may be positioned downstream of the throat 157, which may enhance mixingof the detergent and aerating gas.

FIG. 10 is a cross-sectional view of an embodiment of an in situ foamgenerating air mixer 160. In the illustrated embodiment, the air mixer160 includes an outer fluid path 162 configured to receive liquiddetergent (e.g., citric based detergent), an inner fluid path 164configured to receive aerating gas (e.g., air), and an interface 166between the outer fluid path 162 and the inner fluid path 164. The outerfluid path 162 is disposed between the interface 166 and an outer (e.g.,annular) wall 165 of the air mixer 160. The inner fluid path 164 and theouter fluid path 162 are arranged about a longitudinal axis 149 (e.g.,the inner fluid path 164 and the outer fluid path 162 are concentric andcentered on the longitudinal axis 149). The interface 166 in theillustrated embodiment is a wall having openings 168 through which theair passes from the inner fluid path 164 to a mixing region 167 betweenthe outer fluid path 162 and the outlet 163 (e.g., along the bottleneckbetween the outer fluid path 162 and the outlet 163). The liquiddetergent and the aerating gas may mix within the mixing area 167 togenerate foam, and the foam may be output at an outlet 163 of the airmixer 160. In the illustrated embodiment, the outlet 163 is disposed atthe outer (e.g., annular) wall 165. In some embodiments, the air mixer160 may be oriented (during operation/foam generation) such that Earth'sgravity vector 169 opposes the flow of the detergent and the aeratinggas.

FIG. 11 is a cross-sectional view of another embodiment of an in situfoam generating air mixer 170. In the illustrated embodiment, the airmixer 170 includes an outer fluid path 172 configured to receive liquiddetergent (e.g., citric based detergent), an inner fluid path 174configured to receive aerating gas (e.g., air), and an interface 176between the outer fluid path 172 and the inner fluid path 174. The outerfluid path 172 is disposed between the interface 176 and an outer (e.g.,annular) wall 175 of the air mixer 170. The inner fluid path 174 and theouter fluid path 172 are arranged about a longitudinal axis 149 (e.g.,the inner fluid path 174 and the outer fluid path 172 are concentric andcentered on the longitudinal axis 149). The interface 176 in theillustrated embodiment is a wall having openings 178 through which theair passes from the inner fluid path 174 to the outer fluid path 176.The liquid detergent and the aerating gas may mix within a mixing area177 to generate foam, and the foam may be output at an outlet 173 of theair mixer 170. Ridges 179 positioned on the outer wall 175 of the device170, and protruding inward from the outer wall 175, may facilitatecontrol of a pressure drop adjacent the mixing area 177 and/or enhancemixing of the detergent and air. The outlet 173 is disposed at an end ofthe air mixer 170, as opposed to along the outer (e.g., annular) wall175. In some embodiments, the air mixer 170 may be oriented (duringoperation/foam generation) such that Earth's gravity vector 169 does notoppose the flow of the detergent and the aerating gas. In other words,Earth's gravity vector 169 may cause the detergent and the aerating gasto travel toward the outlet 173 in the illustrated air mixer 170, suchthat liquid detergent does not seep into the inner fluid path 174.

FIG. 12 is a cross-sectional view of another embodiment of an in situfoam generating air mixer 180. In the illustrated embodiment, the airmixer 180 includes an outer fluid path 182 configured to receive liquiddetergent (e.g., citric based detergent), an inner fluid path 184configured to receive aerating gas (e.g., air), and an interface 186between the outer fluid path 182 and the inner fluid path 184. The outerfluid path 182 is disposed between the interface 186 and an outer (e.g.,annular) wall 185 of the air mixer 180. The inner fluid path 184 and theouter fluid path 182 are arranged about a longitudinal axis 149 (e.g.,the inner fluid path 184 and the outer fluid path 182 are concentric andcentered on the longitudinal axis 149). The interface 186 in theillustrated embodiment is a wall having openings 188 through which theair passes from the inner fluid path 184 to the outer fluid path 182.The liquid detergent and the aerating gas may mix within a mixing area187 to generate foam, and the foam may be output at one or more outlets183 of the air mixer 180. The outlets 183 are disposed at the outer(e.g., annular) wall 175, as opposed to an end or end cap of the airmixer 180.

FIG. 13 is a cross-sectional view of embodiment of an in situ foamgenerating porous air mixer 190 having an inner wicking cap 191. In theillustrated embodiment, the porous air mixer 190 includes an outer fluidpath 192 configured to receive liquid detergent (e.g., citric baseddetergent), an inner fluid path 194 configured to receive aerating gas(e.g., air), and an interface 196 between the outer fluid path 192 andthe inner fluid path 194. The outer fluid path 192 is disposed betweenthe interface 196 and an outer (e.g., annular) wall 195 of the porousair mixer 190. The inner fluid path 194 and the outer fluid path 192 arearranged about a longitudinal axis 149 (e.g., the inner fluid path 194and the outer fluid path 192 are concentric and centered on thelongitudinal axis 149). The interface 196 in the illustrated embodimentis an annular wall having the internal wicking cap 191 disposed at anend of the annular wall. The internal wicking cap 191 may be soaked withthe liquid detergent passing through the outer fluid path 192. In theillustrated embodiment, ridges 199 on an inside of the outer (e.g.,annular) wall 195 may protrude radially inward and facilitate control of(e.g., reduce) a pressure drop adjacent the ridges 199, and/or mixing ofthe detergent and air. Further, the aerating gas may pass through theinternal wicking cap 191 having the detergent soaked therein. Thus, asthe aerating gas passes through the detergent-soaked internal wickingcap 191, foam bubbles may be produced within the wicking cap 191, alonga surface 198 of the internal wicking cap 191, and in an area 197immediately downstream of the internal wicking cap 191. The bubbles maybe output at the outlet 193 of the porous air mixer 190 illustrated inFIG. 13 .

FIG. 14 is a cross-sectional view of another embodiment of an in situfoam generating porous air mixer 200 having an end wicking cap 201. Inthe illustrated embodiment, the porous air mixer 200 includes an outerfluid path 202 configured to receive liquid detergent (e.g., citricbased detergent), an inner fluid path 204 configured to receive aeratinggas (e.g., air), and an interface 206 between the outer fluid path 202and the inner fluid path 204. The outer fluid path 202 is disposedbetween the interface 206 and an outer (e.g., annular) wall 205 of theporous air mixer 200. The inner fluid path 204 and the outer fluid path202 are arranged about a longitudinal axis 149 (e.g., the inner fluidpath 204 and the outer fluid path 202 are concentric and centered on thelongitudinal axis 149). The interface 206 in the illustrated embodimentis an annular wall having the end wicking cap 201 disposed at an end ofthe annular wall. The end wicking cap 201 spans between the annular wallof the interface 206 and the outer (e.g., annular) wall 205 radiallyoutward from the outer fluid path 202. The end wicking cap 201 may besoaked with the liquid detergent passing through the outer fluid path202. Further, the aerating gas may pass through the end wicking cap 201having the detergent soaked therein. Thus, as the aerating gas passesthrough the detergent-soaked end wicking cap 201, foam bubbles may beproduced within the end wicking cap 201, along a surface 208 of thewicking cap 201, and in an area 207 immediately downstream of the endwicking cap 201 (e.g., within the fluid passageway of the turbineengine). Accordingly, the outlet 203 in the illustrated embodiment maybe the end wicking cap 201 itself.

FIG. 15 is a cross-sectional view of another embodiment of an in situfoam generating porous air mixer 210 having a porous wicking insert 211.In the illustrated embodiment, the porous air mixer 210 includes anouter fluid path 212 configured to receive aerating gas (e.g., air), aninner fluid path 214 configured to receive liquid detergent (e.g.,citric based detergent), and an interface 216 between the outer fluidpath 212 and the inner fluid path 214. The outer fluid path 212 isdisposed between the interface 216 and an outer (e.g., annular) wall 215of the porous air mixer 210. The inner fluid path 214 and the outerfluid path 212 are arranged about a longitudinal axis 149 (e.g., theinner fluid path 214 and the outer fluid path 212 are concentric andcentered on the longitudinal axis 149). The interface 216 in theillustrated embodiment is an annular wall having the wicking insert 211disposed at an end of the annular wall. The wicking insert 211 may besoaked with the liquid detergent passing through the inner fluid path214. In the illustrated embodiment, the wicking insert 211 between theinner surface of the outer (e.g., annular) wall 215 positioned radiallyoutward from the outer fluid path 212. The wicking insert 211 alsocontacts an end of the annular wall portion of the interface 216. Theaerating gas may pass through the wicking insert 211 having thedetergent soaked therein. Thus, as the aerating gas passes through thedetergent-soaked wicking insert 211, foam bubbles may be produced withinthe wicking insert 211, along a surface 218 of the wicking insert 211,and in an area 217 immediately downstream of the wicking insert 211. Thebubbles may be output at the outlet 213 of the porous air mixer 210illustrated in FIG. 15 .

FIG. 16 is a cross-sectional view of an embodiment of an in situ foamgenerating spinner device 220. In the illustrated embodiment, thespinner device 220 includes an outer fluid path 222 configured toreceive liquid detergent (e.g., citric based detergent), an inner fluidpath 224 configured to receive aerating gas (e.g., air), and aninterface 226 between the outer fluid path 222 and the inner fluid path224. The outer fluid path 222 is disposed between the interface 226 andan outer (e.g., annular) wall 225 of the spinner device 220. The innerfluid path 224 and the outer fluid path 222 are arranged about alongitudinal axis 149 (e.g., the inner fluid path 224 and the outerfluid path 222 are concentric and centered on the longitudinal axis149). The interface 226 in the illustrated embodiment includes a walland a spinner 221 (e.g., fan, blower, fan wheel, blades, etc.). Thespinner 221 may turn to draw the aerating gas toward the spinner 221,and to mix the aerating gas with the detergent flowing through the outerfluid path 222 toward the spinner 221. Thus, foam bubbles may begenerated at the spinner 221 and in an area 227 immediately downstreamfrom the spinner 221. The bubbles may be output at the outlet 223 of thespinner device 220 in the illustrated embodiment.

FIG. 17 is an embodiment of a method 300 of cleaning a turbine engine.In the illustrated embodiment, the method 300 includes inserting (block301) an in situ foam generating device of a foam generating assembly ofa cleaning system into an interior a turbine engine. For example, the insitu foam generating device may be inserted through a port of theturbine engine (e.g., a borescope inspection port, an ignitor port, afuel nozzle orifice, or another port), a throat of the turbine engine,or between blades and a stator of the turbine engine. In someembodiments, the in situ foam generating device (or another portion orcomponent of the foam generating assembly) may include a couplingmechanism that interfaces with (e.g., clamps onto) a feature of theturbine engine, such as a wall of the turbine engine surrounding theport through which the in situ foam generating device is disposed, tomaintain a position of the in situ foam generating device within theinterior of turbine engine.

The method also includes generating (block 302) foam, via the in situfoam generating device, from a detergent and an aerating gas in theinterior (e.g., fluid passageway) of the turbine engine. For example, asdescribed above, the detergent and the aerating gas may be individuallyand/or separately routed to an in situ foam generating device positionedwithin the turbine engine. The in situ foam generating device mayreceive the aerating gas and the detergent, and may mix the aerating gasand the detergent to form the foam. The foam may be output from the insitu foam generating device to an internal area of the turbine engine.

The method 300 also includes soaking (block 304) a fluid passageway ofthe turbine engine with the foam. For example, the foam may contactsurfaces of the turbine engine and may soak the surfaces of the turbineengine for a period of time. In some embodiments, the turbine engine maybe turned as the foam travels through the turbine engine, which maycause the foam to contact a greater number or percentage of surfaces ofthe turbine engine.

The method 300 may also include rinsing or flushing (block 306) thefluid passageway of the turbine engine after the above-described soakingprocedure. For example, as the foam contacts the surfaces of the turbineengine in the fluid passageway, the foam may loosen, break down, orotherwise remove contaminants disposed on the surfaces of the turbineengine. As the contaminants are removed, the foam may collapse into aneffluent having the detergent, the contaminants, and other materials(e.g., surfactants) that may be mixed with, or a part of, the detergent.The effluent may then be rinsed or flushed from the fluid passageway.

It should be noted that the method 300 may include the use of several insitu foam generating devices configured to generate foam at variouslocations internal to the turbine engine. For example, the in situ foamgenerating devices may be inserted through various ports and orifices ofthe turbine engine. Each in situ foam generating device may includeindependent aerating gas and detergent sources, or the in situ foamgenerating devices may receive aerating gas form the same aerating gassource, and detergent from the same detergent source. By utilizingmultiple in situ foam generating devices simultaneously, several targetsinternal to the turbine engine can be cleaned simultaneously, and thefoam generated by each foam generating device is only responsible forcleaning areas adjacent to the particular device. Further still, the insitu foam generating devices may be used exclusively, or together withother foam generating assemblies or devices that clean certain portionsof the turbine engine.

Technical effects of the invention include improved cleaning accuracy,improved cleaning efficiency, and cost savings over traditionalembodiments having external foam generation. For example, as describedabove, in situ foam generation reduces a traversal distance of thegenerated foam between the generating device and the target cleaningsurface in the interior of the turbine engine. By reducing the traversaldistance, bubble diameters and bubble collapse are more controllable.Further, for the above reasons, more cost effective materials (e.g.,having a lower foam stability) may be used to achieve the same or bettercleaning results (e.g., accuracy, efficiency) compared to traditionalembodiments having external foam generation.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

The invention claimed is:
 1. A turbine system, comprising: a turbineengine; an aerating gas hose; a water-based foaming liquid detergenthose; and an in situ foam generating device disposed in the turbineengine, wherein the in situ foam generating device comprises a maximumwidth sized to pass through a minimum width of a port of the turbineengine, wherein the in situ foam generating device is coupled to theaerating gas hose passing through the port of the turbine engine and thewater-based foaming liquid detergent hose passing through the port ofthe turbine engine, wherein the in situ foam generating device comprisesa body having a first end, a second end, and an outer wall extendingfrom the first end to the second end and having the maximum width of thein situ foam generating device, wherein the aerating gas hose and thewater-based foaming liquid detergent hose are coupled to the first endinward from the maximum width of the outer wall, and wherein the in situfoam generating device comprises: an inner fluid path and an outer fluidpath at least partially surrounding the inner fluid path, wherein theinner fluid path is configured to receive one of a water-based foamingliquid detergent from the water-based foaming liquid detergent hose oran aerating gas from the aerating gas hose, and wherein the outer fluidpath is configured to receive the other of the water-based foamingliquid detergent from the water-based foaming liquid detergent hose orthe aerating gas from the aerating gas hose, respectively; and aninterface between the inner fluid path and the outer fluid path, whereinthe interface is configured to enable mixing of the aerating gas withthe water-based foaming liquid detergent to generate foam.
 2. Theturbine system of claim 1, wherein the interface comprises a walldisposed between the inner fluid path and the outer fluid path, whereinthe wall comprises openings fluidly coupling the inner fluid path andthe outer fluid path.
 3. The turbine system of claim 1, wherein the portis a borescope inspection port.
 4. The turbine system of claim 1,wherein the aerating gas is air or nitrogen.
 5. The turbine system ofclaim 1, wherein the inner fluid path is configured to receive thewater-based foaming liquid detergent from the water-based foaming liquiddetergent hose, and wherein the outer fluid path is configured toreceive the aerating gas from the aerating gas hose.
 6. The turbinesystem of claim 1, wherein the outer fluid path is configured to receivethe water-based foaming liquid detergent from the water-based foamingliquid detergent hose, and wherein the inner fluid path is configured toreceive the aerating gas from the aerating gas hose.
 7. The turbinesystem of claim 2, wherein the in situ foam generating device is an insitu foam generating eductor, wherein a structure of the eductor isconfigured to enable a flow of the aerating gas through a throat of theinner fluid path to cause a low pressure area proximate the openings ofthe interface that draws the water-based foaming liquid detergentthrough the openings of the interface.
 8. The turbine system of claim 1,wherein the in situ foam generating device is an in situ foam generatingair mixer.
 9. The turbine system of claim 1, wherein the in situ foamgenerating device has an outlet disposed at an outer annular wall. 10.The turbine system of claim 1, wherein the in situ foam generatingdevice has an outlet disposed at an end of the in situ foam generatingdevice.